1. Field of the Invention
The present invention relates to an imaging apparatus, a high frequency component detection circuit, a high frequency component detection method and a computer program product. Particularly, the present invention relates to technologies applied to the imaging apparatus, high frequency component detection circuit, high frequency component detection method and computer program product that detect a high frequency component included in a video signal and perform noise reduction processing and the like.
2. Description of the Related Art
In the past, in the case of removing noise included in a video signal, if a high frequency component included in the video signal was detected, such component was retained without removing the noise from a portion where the high frequency component was detected. Since the edge of images and the like are maintained by thus retaining the high frequency component, the picture quality can be maintained without deterioration caused by removing the noise.
FIG. 1 shows an example of configuration of a noise reduction circuit of this kind in related art. In this example, three primary color signals R (red), G (green) and B (blue) are supplied to a high-pass filter 98 and only high frequency components are extracted. The high frequency components extracted in the high-pass filter 98 are supplied to a noise reduction circuit 99 where noise reduction processing is not performed on portions detected to be the high frequency components, or processing of reducing the noise reduction effect or the like is performed thereon. A high-pass filter passing only a signal component having a frequency equal to or higher than a predetermined high frequency can be applied as the high-pass filter 98, for example.
Noise reduction processing is thus controlled based on the detection of a high frequency component, and therefore a high frequency signal component such as the edge of an image can be maintained after removing the noise.
Japanese Unexamined Patent Application Publication No. 2003-242504 discloses noise reduction processing corresponding to a luminance level.